iPad Kindle app error 401

[Jobos]

So I've put the Kindle app on 30 iPads but all give the error 'Device Registration Failed. The operation couldn't be completed. (HTTPErrorCode error 401.)'

 

I've called Amazon support who say they haven't see this error before which I find very odd and when asked what port the app uses they didn't know. I'm thinking the firewall or filter is blocking the app talking to Amazon. Has anyone seen this error before or know what might be causing it?

[pete]

401 is unauthorised and comes from a webserver, typically.

 

407 would be the proxy saying auth required.